Pearson Algebra 1 Common Core, 2015
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Pearson Algebra 1 Common Core, 2015 View details
5. Standard Form
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Exercise 1 Page 325

To determine the x- and y-intercepts of a line, we need to substitute 0 for one variable, solve, then repeat for the other variable.

Finding the x-intercept

Think of the point where the graph of an equation crosses the x-axis. The y-value of that ( x, y) coordinate pair is 0, and the x-value is the x-intercept. To find the x-intercept of the equation, we should substitute 0 for y and solve for x.
3x-4y=9
3x-4( 0)=9
3x=9
x=3
An x-intercept of 3 means that the graph passes through the x-axis at the point ( 3,0).

Finding the y-intercept

Let's use the same concept to find the y-intercept. Consider the point where the graph of the equation crosses the y-axis. The x-value of the ( x, y) coordinate pair at the y-intercept is 0. Therefore, substituting 0 for x will give us the y-intercept.
3x-4y=9
3( 0)-4y=9
-4y=9
y=9/-4
y=-9/4
A y-intercept of - 94 means that the graph passes through the y-axis at the point (0, - 94).